Yep, I'm sure you'll be spending a lot of time on the trainer,especially during the winter months (In colorado, that's November thru April). Initially this is a good thing anyway, because you can focus on acclimating to the elevation.
Depending on your fitness and a slew of other variables, it could take up to a month to really become used to the altitude. I'm up at 7300 feet, so our town is a bit higher than most. It took me what seemed like forever to get a nice endurance base for doing the "little" hills around here that top out at around 9300 feet.
Do lots of time in the lower heart rate zones and mix in the occasional interval routine to see how you're progressing. Check around for riding groups also. Start with the slower end of the group, even if you typically ride with the A group. Build up and you'll adjust fine.